Various types of latching mechanisms for overhead-type doors are well known in the art. For example, mechanisms are known for automatically latching a door when it is moved to its closed position so that simple closing of the door insures that the door will remain closed unless some positive act or effort to open the door is undertaken. Such mechanisms are advantageous for preventing unwanted entry or intrusions as well as eliminating the necessity of remembering to engage a lock or latch after the door is closed. Also, such mechanisms are useful in those instances where it might be desired that a specific sequence of operations be followed in order to open the door. For instance, automatic latching of overhead doors in their closed position is desirable with respect to doors in warehouses and the like in order to discourage attempts to open the doors with forklifts, which have often resulted in damage to the doors, as opposed to pulling of a chain or cable connected to the door. By providing an automatic latching mechanism for latching the door closed, persons could be required to disembark from the forklift and then pull on a cable connected to the door to effect opening, thus minimizing the risks of damage to the door.
Similarly, various latching mechanisms are known for automatically latching of the doors when they have been moved into their raised position to provide access through the door opening. These latter types of latching mechanisms are often desirable and advantageous in serving as safety devices to protect against injury to personnel or equipment as a result of an accidental closing of the door. In such instances, the latching mechanism serves to latch and hold the door in the raised position until some positive action or effort is undertaken to release the door.
Some of these various prior art latching or locking mechanisms are very complex and complicated. While other of the prior art mechanisms are of a relatively simplistic design, none of the prior art mechanisms of which the inventor is aware disclose a latching mechanism which is operative to automatically latch an overhead door in both the raised and lowered positions when the door is moved to such positions.
More particularly, one example of a prior art latching mechanism for automatically latching an overhead-type door when it is lowered to its closed position is shown in U.S. Pat. No. 2,917,335. This patent discloses a rather complicated latching mechanism which includes a projection secured to the overhead frame of the enclosure which is adapted to enter and engage a bracket fixed to the upper end of the door when the door is closed, the projection being held by means of a rotary-type locking mechanism. Release of the projection is achieved by means of a cable or chain connected to a portion of the rotary locking mechanism so that when the chain is pulled the rotary mechanism is moved to a position to allow the door to be opened.
U.S. Pat. No. 2,971,790 illustrates an overhead door safety device for preventing accidental dislodging or closing of a door after it has been moved to its opened position. In accordance with this reference, the safety device includes a fixture adapted to be mounted to a horizontal frame member of the door enclosure and having a pivotable stop latch or lever mounted therein. The latch member is pivotable between a first horizontal position and a second upwardly inclined position. A bracket is secured to the lower front portion of the door, and includes an upwardly facing flange which, when the door is raised, is operative to pivot the latched member upwardly to allow the bracket to pass thereby. However, when the door is in its fully raised position, any movement of the door downwardly serves to cause the outwardly protruding lip of the flange to engage the stop lever and thus prevent further downward movement of the door. In order to allow the door to close fully, the stop lever must be pivoted to its inclined position by virtue of a downwardly depending pull cord secured to one end of the stop latch.
U.S. Pat. Nos. 1,558,917; 1,470,029; 2,123,188 and 2,168,635 are each directed to locking mechanisms for swinging doors and the like. While each of these references disclose the employment of pivotable members for holding the doors in whatever position they are placed, they are not directed to the employment of such pivotable members with respect to the overhead-type doors. Also, in each of these references, the pivotable members are secured directly to the doors and are operative to engage the ground or floor by pivoting of the pivotable members downwardly. Such mechanisms, however, could not be used in such manner with respect to overhead-type doors.
Accordingly, it is apparent that a need exists for an automatic latching mechanism for overhead-type doors which is operative to automatically latch the door in the raised and closed positions. At the same time, the latching mechanism should not be of a highly complex and complicated design, nor require significant and expensive modifications to existing overhead doors in order for use in connection therewith. Rather, it is desirable that the latching mechanism be readily and easily adapted for retrofitting with respect to existing overhead-type doors.